--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1Allocator.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,489 @@
+/*
+ * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc/g1/g1Allocator.inline.hpp"
+#include "gc/g1/g1AllocRegion.inline.hpp"
+#include "gc/g1/g1EvacStats.inline.hpp"
+#include "gc/g1/g1CollectedHeap.inline.hpp"
+#include "gc/g1/heapRegion.inline.hpp"
+#include "gc/g1/heapRegionSet.inline.hpp"
+#include "utilities/align.hpp"
+
+G1DefaultAllocator::G1DefaultAllocator(G1CollectedHeap* heap) :
+ G1Allocator(heap),
+ _survivor_is_full(false),
+ _old_is_full(false),
+ _retained_old_gc_alloc_region(NULL),
+ _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)),
+ _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) {
+}
+
+void G1DefaultAllocator::init_mutator_alloc_region() {
+ assert(_mutator_alloc_region.get() == NULL, "pre-condition");
+ _mutator_alloc_region.init();
+}
+
+void G1DefaultAllocator::release_mutator_alloc_region() {
+ _mutator_alloc_region.release();
+ assert(_mutator_alloc_region.get() == NULL, "post-condition");
+}
+
+void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info,
+ OldGCAllocRegion* old,
+ HeapRegion** retained_old) {
+ HeapRegion* retained_region = *retained_old;
+ *retained_old = NULL;
+ assert(retained_region == NULL || !retained_region->is_archive(),
+ "Archive region should not be alloc region (index %u)", retained_region->hrm_index());
+
+ // We will discard the current GC alloc region if:
+ // a) it's in the collection set (it can happen!),
+ // b) it's already full (no point in using it),
+ // c) it's empty (this means that it was emptied during
+ // a cleanup and it should be on the free list now), or
+ // d) it's humongous (this means that it was emptied
+ // during a cleanup and was added to the free list, but
+ // has been subsequently used to allocate a humongous
+ // object that may be less than the region size).
+ if (retained_region != NULL &&
+ !retained_region->in_collection_set() &&
+ !(retained_region->top() == retained_region->end()) &&
+ !retained_region->is_empty() &&
+ !retained_region->is_humongous()) {
+ retained_region->record_timestamp();
+ // The retained region was added to the old region set when it was
+ // retired. We have to remove it now, since we don't allow regions
+ // we allocate to in the region sets. We'll re-add it later, when
+ // it's retired again.
+ _g1h->old_set_remove(retained_region);
+ bool during_im = _g1h->collector_state()->during_initial_mark_pause();
+ retained_region->note_start_of_copying(during_im);
+ old->set(retained_region);
+ _g1h->hr_printer()->reuse(retained_region);
+ evacuation_info.set_alloc_regions_used_before(retained_region->used());
+ }
+}
+
+void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
+ assert_at_safepoint(true /* should_be_vm_thread */);
+
+ _survivor_is_full = false;
+ _old_is_full = false;
+
+ _survivor_gc_alloc_region.init();
+ _old_gc_alloc_region.init();
+ reuse_retained_old_region(evacuation_info,
+ &_old_gc_alloc_region,
+ &_retained_old_gc_alloc_region);
+}
+
+void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) {
+ AllocationContext_t context = AllocationContext::current();
+ evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() +
+ old_gc_alloc_region(context)->count());
+ survivor_gc_alloc_region(context)->release();
+ // If we have an old GC alloc region to release, we'll save it in
+ // _retained_old_gc_alloc_region. If we don't
+ // _retained_old_gc_alloc_region will become NULL. This is what we
+ // want either way so no reason to check explicitly for either
+ // condition.
+ _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release();
+}
+
+void G1DefaultAllocator::abandon_gc_alloc_regions() {
+ assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
+ assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
+ _retained_old_gc_alloc_region = NULL;
+}
+
+bool G1DefaultAllocator::survivor_is_full(AllocationContext_t context) const {
+ return _survivor_is_full;
+}
+
+bool G1DefaultAllocator::old_is_full(AllocationContext_t context) const {
+ return _old_is_full;
+}
+
+void G1DefaultAllocator::set_survivor_full(AllocationContext_t context) {
+ _survivor_is_full = true;
+}
+
+void G1DefaultAllocator::set_old_full(AllocationContext_t context) {
+ _old_is_full = true;
+}
+
+G1PLAB::G1PLAB(size_t gclab_word_size) :
+ PLAB(gclab_word_size), _retired(true) { }
+
+size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) {
+ // Return the remaining space in the cur alloc region, but not less than
+ // the min TLAB size.
+
+ // Also, this value can be at most the humongous object threshold,
+ // since we can't allow tlabs to grow big enough to accommodate
+ // humongous objects.
+
+ HeapRegion* hr = mutator_alloc_region(context)->get();
+ size_t max_tlab = _g1h->max_tlab_size() * wordSize;
+ if (hr == NULL) {
+ return max_tlab;
+ } else {
+ return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
+ }
+}
+
+HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
+ size_t word_size,
+ AllocationContext_t context) {
+ size_t temp = 0;
+ HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp, context);
+ assert(result == NULL || temp == word_size,
+ "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
+ word_size, temp, p2i(result));
+ return result;
+}
+
+HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,
+ size_t min_word_size,
+ size_t desired_word_size,
+ size_t* actual_word_size,
+ AllocationContext_t context) {
+ switch (dest.value()) {
+ case InCSetState::Young:
+ return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);
+ case InCSetState::Old:
+ return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);
+ default:
+ ShouldNotReachHere();
+ return NULL; // Keep some compilers happy
+ }
+}
+
+HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,
+ size_t desired_word_size,
+ size_t* actual_word_size,
+ AllocationContext_t context) {
+ assert(!_g1h->is_humongous(desired_word_size),
+ "we should not be seeing humongous-size allocations in this path");
+
+ HeapWord* result = survivor_gc_alloc_region(context)->attempt_allocation(min_word_size,
+ desired_word_size,
+ actual_word_size,
+ false /* bot_updates */);
+ if (result == NULL && !survivor_is_full(context)) {
+ MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
+ result = survivor_gc_alloc_region(context)->attempt_allocation_locked(min_word_size,
+ desired_word_size,
+ actual_word_size,
+ false /* bot_updates */);
+ if (result == NULL) {
+ set_survivor_full(context);
+ }
+ }
+ if (result != NULL) {
+ _g1h->dirty_young_block(result, *actual_word_size);
+ }
+ return result;
+}
+
+HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,
+ size_t desired_word_size,
+ size_t* actual_word_size,
+ AllocationContext_t context) {
+ assert(!_g1h->is_humongous(desired_word_size),
+ "we should not be seeing humongous-size allocations in this path");
+
+ HeapWord* result = old_gc_alloc_region(context)->attempt_allocation(min_word_size,
+ desired_word_size,
+ actual_word_size,
+ true /* bot_updates */);
+ if (result == NULL && !old_is_full(context)) {
+ MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
+ result = old_gc_alloc_region(context)->attempt_allocation_locked(min_word_size,
+ desired_word_size,
+ actual_word_size,
+ true /* bot_updates */);
+ if (result == NULL) {
+ set_old_full(context);
+ }
+ }
+ return result;
+}
+
+G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :
+ _g1h(G1CollectedHeap::heap()),
+ _allocator(allocator),
+ _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
+ for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) {
+ _direct_allocated[i] = 0;
+ }
+}
+
+bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {
+ return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);
+}
+
+HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest,
+ size_t word_sz,
+ AllocationContext_t context,
+ bool* plab_refill_failed) {
+ size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest);
+ size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);
+
+ // Only get a new PLAB if the allocation fits and it would not waste more than
+ // ParallelGCBufferWastePct in the existing buffer.
+ if ((required_in_plab <= plab_word_size) &&
+ may_throw_away_buffer(required_in_plab, plab_word_size)) {
+
+ G1PLAB* alloc_buf = alloc_buffer(dest, context);
+ alloc_buf->retire();
+
+ size_t actual_plab_size = 0;
+ HeapWord* buf = _allocator->par_allocate_during_gc(dest,
+ required_in_plab,
+ plab_word_size,
+ &actual_plab_size,
+ context);
+
+ assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),
+ "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,
+ required_in_plab, plab_word_size, actual_plab_size, p2i(buf));
+
+ if (buf != NULL) {
+ alloc_buf->set_buf(buf, actual_plab_size);
+
+ HeapWord* const obj = alloc_buf->allocate(word_sz);
+ assert(obj != NULL, "PLAB should have been big enough, tried to allocate "
+ SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,
+ word_sz, required_in_plab, plab_word_size);
+ return obj;
+ }
+ // Otherwise.
+ *plab_refill_failed = true;
+ }
+ // Try direct allocation.
+ HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context);
+ if (result != NULL) {
+ _direct_allocated[dest.value()] += word_sz;
+ }
+ return result;
+}
+
+void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) {
+ alloc_buffer(dest, context)->undo_allocation(obj, word_sz);
+}
+
+G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) :
+ G1PLABAllocator(allocator),
+ _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)),
+ _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) {
+ for (uint state = 0; state < InCSetState::Num; state++) {
+ _alloc_buffers[state] = NULL;
+ }
+ _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer;
+ _alloc_buffers[InCSetState::Old] = &_tenured_alloc_buffer;
+}
+
+void G1DefaultPLABAllocator::flush_and_retire_stats() {
+ for (uint state = 0; state < InCSetState::Num; state++) {
+ G1PLAB* const buf = _alloc_buffers[state];
+ if (buf != NULL) {
+ G1EvacStats* stats = _g1h->alloc_buffer_stats(state);
+ buf->flush_and_retire_stats(stats);
+ stats->add_direct_allocated(_direct_allocated[state]);
+ _direct_allocated[state] = 0;
+ }
+ }
+}
+
+void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) {
+ wasted = 0;
+ undo_wasted = 0;
+ for (uint state = 0; state < InCSetState::Num; state++) {
+ G1PLAB * const buf = _alloc_buffers[state];
+ if (buf != NULL) {
+ wasted += buf->waste();
+ undo_wasted += buf->undo_waste();
+ }
+ }
+}
+
+bool G1ArchiveAllocator::_archive_check_enabled = false;
+G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map;
+G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map;
+
+G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) {
+ // Create the archive allocator, and also enable archive object checking
+ // in mark-sweep, since we will be creating archive regions.
+ G1ArchiveAllocator* result = new G1ArchiveAllocator(g1h, open);
+ enable_archive_object_check();
+ return result;
+}
+
+bool G1ArchiveAllocator::alloc_new_region() {
+ // Allocate the highest free region in the reserved heap,
+ // and add it to our list of allocated regions. It is marked
+ // archive and added to the old set.
+ HeapRegion* hr = _g1h->alloc_highest_free_region();
+ if (hr == NULL) {
+ return false;
+ }
+ assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());
+ if (_open) {
+ hr->set_open_archive();
+ } else {
+ hr->set_closed_archive();
+ }
+ _g1h->old_set_add(hr);
+ _g1h->hr_printer()->alloc(hr);
+ _allocated_regions.append(hr);
+ _allocation_region = hr;
+
+ // Set up _bottom and _max to begin allocating in the lowest
+ // min_region_size'd chunk of the allocated G1 region.
+ _bottom = hr->bottom();
+ _max = _bottom + HeapRegion::min_region_size_in_words();
+
+ // Tell mark-sweep that objects in this region are not to be marked.
+ set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open);
+
+ // Since we've modified the old set, call update_sizes.
+ _g1h->g1mm()->update_sizes();
+ return true;
+}
+
+HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {
+ assert(word_size != 0, "size must not be zero");
+ if (_allocation_region == NULL) {
+ if (!alloc_new_region()) {
+ return NULL;
+ }
+ }
+ HeapWord* old_top = _allocation_region->top();
+ assert(_bottom >= _allocation_region->bottom(),
+ "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,
+ p2i(_bottom), p2i(_allocation_region->bottom()));
+ assert(_max <= _allocation_region->end(),
+ "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,
+ p2i(_max), p2i(_allocation_region->end()));
+ assert(_bottom <= old_top && old_top <= _max,
+ "inconsistent allocation state: expected "
+ PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,
+ p2i(_bottom), p2i(old_top), p2i(_max));
+
+ // Allocate the next word_size words in the current allocation chunk.
+ // If allocation would cross the _max boundary, insert a filler and begin
+ // at the base of the next min_region_size'd chunk. Also advance to the next
+ // chunk if we don't yet cross the boundary, but the remainder would be too
+ // small to fill.
+ HeapWord* new_top = old_top + word_size;
+ size_t remainder = pointer_delta(_max, new_top);
+ if ((new_top > _max) ||
+ ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {
+ if (old_top != _max) {
+ size_t fill_size = pointer_delta(_max, old_top);
+ CollectedHeap::fill_with_object(old_top, fill_size);
+ _summary_bytes_used += fill_size * HeapWordSize;
+ }
+ _allocation_region->set_top(_max);
+ old_top = _bottom = _max;
+
+ // Check if we've just used up the last min_region_size'd chunk
+ // in the current region, and if so, allocate a new one.
+ if (_bottom != _allocation_region->end()) {
+ _max = _bottom + HeapRegion::min_region_size_in_words();
+ } else {
+ if (!alloc_new_region()) {
+ return NULL;
+ }
+ old_top = _allocation_region->bottom();
+ }
+ }
+ _allocation_region->set_top(old_top + word_size);
+ _summary_bytes_used += word_size * HeapWordSize;
+
+ return old_top;
+}
+
+void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,
+ size_t end_alignment_in_bytes) {
+ assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),
+ "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);
+ assert(is_aligned(end_alignment_in_bytes, HeapWordSize),
+ "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);
+
+ // If we've allocated nothing, simply return.
+ if (_allocation_region == NULL) {
+ return;
+ }
+
+ // If an end alignment was requested, insert filler objects.
+ if (end_alignment_in_bytes != 0) {
+ HeapWord* currtop = _allocation_region->top();
+ HeapWord* newtop = align_up(currtop, end_alignment_in_bytes);
+ size_t fill_size = pointer_delta(newtop, currtop);
+ if (fill_size != 0) {
+ if (fill_size < CollectedHeap::min_fill_size()) {
+ // If the required fill is smaller than we can represent,
+ // bump up to the next aligned address. We know we won't exceed the current
+ // region boundary because the max supported alignment is smaller than the min
+ // region size, and because the allocation code never leaves space smaller than
+ // the min_fill_size at the top of the current allocation region.
+ newtop = align_up(currtop + CollectedHeap::min_fill_size(),
+ end_alignment_in_bytes);
+ fill_size = pointer_delta(newtop, currtop);
+ }
+ HeapWord* fill = archive_mem_allocate(fill_size);
+ CollectedHeap::fill_with_objects(fill, fill_size);
+ }
+ }
+
+ // Loop through the allocated regions, and create MemRegions summarizing
+ // the allocated address range, combining contiguous ranges. Add the
+ // MemRegions to the GrowableArray provided by the caller.
+ int index = _allocated_regions.length() - 1;
+ assert(_allocated_regions.at(index) == _allocation_region,
+ "expected region %u at end of array, found %u",
+ _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());
+ HeapWord* base_address = _allocation_region->bottom();
+ HeapWord* top = base_address;
+
+ while (index >= 0) {
+ HeapRegion* next = _allocated_regions.at(index);
+ HeapWord* new_base = next->bottom();
+ HeapWord* new_top = next->top();
+ if (new_base != top) {
+ ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
+ base_address = new_base;
+ }
+ top = new_top;
+ index = index - 1;
+ }
+
+ assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));
+ ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));
+ _allocated_regions.clear();
+ _allocation_region = NULL;
+};